Simultaneous Subaru/MAGNUMObservations of Extrasolar Planetary TransitsNorio Narita(U. Tokyo, JSPS Fellow, Japan)

Collaborators

Y. Ohta, A. Taruya, Y. Suto, (U. Tokyo)B. Sato, M. Tamura, T. Yamada, W Aoki, (NAOJ)K. Enya, (JAXA) J. N. Winn, (MIT) E. L. Turner, (Princeton)1 / 18

ContentsTwo Japanese Telescopes in HawaiiResearch ProjectsTransmission SpectroscopyMeasurements of the Rossiter effectPrevious and Ongoing WorkSensitivity and FeasibilityFuture Prospects2 / 18

Japanese Telescopes in HawaiiSubaru 8.2m Telescopeat Mauna Kea, the Big IslandMUGNUM 2m Telescopeat Haleakala, Maui.3 / 18

Subaru HDS (High Dispersion Spectrograph)Instrumental performance:for V = 8 stars (in 5000 ~ 6000 )R ~ 90000, 3 min exposure SNR ~ 250 / pixelfor V = 12 starsR ~ 45000, 15 min exposure SNR ~ 100 / pixelHDS is an echelle spectrographinstalled at Subaru Telescope.An iodine cell is available forradial velocity measurements.4 / 18

Multicolor Active Galactic NUclei MonitoringMAGNUM is a dedicatedtelescope for AGN research.Instrumental performance:FOV : 1.5 x 1.5 square, Band : Optical & IRdifferential photometric accuracy~ 1.5 mmag (in FOV)4 ~ 6 mmag (nodding out of FOV)A wide-field camera has not yet been equipped (future planning).5 / 18

Research Projects using these TelescopesAim: to characterize exoplanets and their systemsthrough transit observationsGround-based Transmission Spectroscopysearch for atmospheric signaturesprevious work : HD 209458

Measurements of the Rossiter effectmeasure the angle between stellar-spin and planetary-orbital axesongoing work : TrES-16 / 18

Observing StrategiesSimultaneous spectroscopy and photometry:to minimize uncertainty due to orbital ephemerisimportant for the Rossiter measurementstransit center accuracy of a few minutesto monitor transient stellar activitiesflare, spots, etcFull transit observation within a single night:to limit day-to-day instrumental or telluric variationsimportant for transmission spectroscopy7 / 18

Transmission SpectroscopyOne can in principle detect atmospheric constituentsby comparing spectra taken in and out of transit.8 / 18

Early Theoretical ModelsExcess 0.1~0.2% absorption was predicted in alkali metal lineswith clouds at low pressure (deep cloud decks).9 / 18

HST ResultsDetection of -0.02320.0057 % excess absorptionfor 12 band around the sodium doublet:However, it was significantly weakerthan the fiducial models (for HD 209458b at least).10 / 18

Previous Work using Subaru HDSOur sensitivity for HD 209458b was enough to excludeprevious fiducial models with a single night observation.We have attempted to search atmospheric signatures:11 / 18

Motivation of ground-based observationsHow about other transiting hot Jupiters?We can answer whether the weak sodium absorption is standard or not,or we would be able to detect excess absorption.12 / 18

Measurements of the Rossiter Effectgive us clues to learn about formation mechanism of exoplanets.misalignment parameter the degree between the stellar spin axis and the planetary orbital axisin sky projection.13 / 18

Some Models of Hot Jupiter Formation14 / 18

Past ResultsAll results consistent with zero-misalignment.HD 209458 (V = 7.65)-4.4 1.4 deg (Winn et al. 2005)HD 149026 (V = 8.15)11 14 deg (Wolf et al. 2006)HD 189733 (V = 7.67)-1.4 1.1 deg (Winn et al. ApJL submitted)All hot Jupiters seem to be formed by standard migration theories.15 / 18

Ongoing WorkWe observed TrES-1 (V = 11.8) covering a full transit.We have confirmed transit time by photometry, andobtained 23 radial velocity samples (8~10 m/s accuracy).MAGNUM photometry (1 ~ 0.15%)Subaru spectroscopy (SNR ~ 80)16 / 18

Motivation and Future WorkPlanetary systems with large have not yet discovered.Migration mechanism is unique standard?17 / 18

SummaryOur group has initiated transit observation projects:Ground-based Transmission SpectroscopyMeasurements of the Rossiter effect

Our targets are:V < 8 (Transmission Spectroscopy)V < 12 (the Rossiter measurements)HD189733, HAT-P-1, etc would be good targets

We wish to provide new observational information through our projects.18 / 18

acronym